C# extension method to discover if a property is a collection

PropertyInfoExtensions_IsEnumerable.cs

using System.Collections.Generic;
using System.Reflection;

public static class PropertyInfoExtensions
{
    public static bool IsEnumerable(this PropertyInfo property) =>
        (property.PropertyType.IsGenericType &&
         property.PropertyType.GetGenericTypeDefinition() == typeof(IEnumerable<>)) ||
        property.PropertyType.GetInterface(typeof(IEnumerable<>).FullName) != null;
}